This invention relates to an improved method and apparatus for unassisted stretching, exercising and strengthening of the muscles of the lower back and legs, and more particularly to a method and portable apparatus which may be easily employed by users of all abilities, heights and varying body lengths between hips and shoulders for unassisted proprioceptive neuromuscular facilitation (PNF).
PNF is a common stretching technique. A method for stretching hamstring and lower back muscles and strengthening such muscles using PNF is described in The Goodbye Back Pain Handbook by James A. Peterson et al. (Masters Press, 5025 28th St., S. E., Grand Rapids, Mich. 49506). In the disclosed technique, the patient lies on a padded board and is restrained around the waist with a strap to stabilize the pelvis. A second person then places one foot on the board and lifts the patient's legs by the ankles upwardly toward the head in a repetitive manner to stretch the lower back and hamstring muscles. The same muscles are strengthened by having the assistant provide controlled resistance to downward movement of the legs.
While the above exercises and method have been proven effective, the method requires the use of an assistant or so-called training partner, preferably who has experience or training with the system. The requirement of an assistant limits the practical usage and availability of the method. U.S. Pat. No. 5,067,709 to Christianson discloses an apparatus for exercising and strengthening the muscles of the lower back which is intended to allow an individual to utilize the above described stretching technique without an assistant. The Christianson device comprises two components, a pelvis board with a strap for retaining the pelvis and a rope and pulley system for raising the legs. The rope and pulley system is connected between the feet or legs of the user and a support above the head of the user. The pulley system is a "block and tackle" type arrangement that allows the user a mechanical advantage in raising the legs. One of the pulleys also includes a clutch device to provide resistance when the legs are lowered. In the Christianson device, both of the user's feet or legs are held together in a supporting sling. The free end of the rope is grasped by the user. By pulling or releasing the rope, the user is able to pull the legs upwardly toward the head, and to gradually lower the legs toward the floor with resistance against the clutch device.
While providing for unassisted exercise, the Christianson device has a number of drawbacks. For example, the user must directly grip the rope, which can be difficult or fatiguing to the hands. To reduce this problem, Christianson has employed the relatively complex pulley system. Also, the arrangement of the rope and sling allows only both legs to be raised together, which may be undesirable or impossible for some users. In order to use the device with one leg at a time, the user would have to stop exercising and switch the sling from one leg to another.
A number of other exercise devices are known in the art and that exhibit similar disadvantages to Christianson. One example is the apparatus described in U.S. Pat. No. 3,117,782 to Johnston. The Johnston patent discloses an exercise apparatus which includes a back supporting mat and a cable and pulley system. The Johnston cable terminates at each end with a handle and forms a single harness in the middle that secures both legs together at the ankles. The user of the Johnston device lies down, inserts both feet into the harness, reaches up to grab a respective handle and raises or lowers both legs by swinging his arms in an arc between a position parallel to the floor and a position well back of the head. The Johnston apparatus is thus also limited to use with both feet together without stopping and removing the harness.
Other devices exhibiting one or more of the above drawbacks are disclosed in U.S. Pat. Nos. 1,144,085, 4,084,815 and Swiss patent No. 407833.
While the above described devices may be effective in the case of certain users, they do not satisfactorily account for the needs of all potential users of varying ability who are lower pack pain sufferers and wish to progress gradually in their muscle stretching and strengthening exercises.